Washington (CNN) – A family friend says Ted Kennedy Jr., son of the late Sen. Edward Kennedy, is seriously considering running for senate if John Kerry vacates the seat to become the next secretary of state.

Kerry is said to be the frontrunner to succeed Secretary of State Hillary Clinton, who is leaving her post next year.

Friends and some Democratic Party leaders are encouraging Kennedy to run for the Massachusetts seat held by Kerry since 1985.

“He is listening to everyone, but he is not going to make a decision unless there is an open seat,” said the friend, who noted telephone calls to Kennedy urging him to run have increased in the past 48 hours.

Brown lost his own re-election bid in November, a defeat attributed to a well-funded opponent in Elizabeth Warren and a strong Democratic turnout in a presidential election year.

In 2010, Brown won a special election to fill the late Kennedy’s unexpired term.

“What we have in Massachusetts with some of the names being discussed is that they are not well known, they have a statewide name ID problem,” said a Massachusetts Democratic operative, who is not associated with the Kennedys. “Ted Kennedy Jr. does not have that problem.”

Several Massachusetts Democrats, including Reps. Michael Capuano, Ed Markey, and Stephen Lynch, are interested in running for the seat should Kerry vacate it.

Kennedy was not tested in the WBUR poll, but the “Kennedy” name continues to carry a lot of weight in Massachusetts politics. Last month, Ted Kennedy Jr.’s cousin, Joseph Kennedy III, was elected to represent Massachusetts in Congress.

Kennedy, who heads a health care financial services company, lives in Connecticut but owns a home on Cape Cod. His younger brother, Patrick, served Rhode Island in Congress from 1995 until 2011.